THE SESSILE BABNACLES. 



145 



Height 73 mm., greatest diameter 3G mm., diameters of base 27 

 and 28^ mm. (Unalaska, on a sponge). 



The Librum has two minute teeth on each side. Palpi simihir to 

 those of B. hahrnus. 



The mandibles of No. 38667 have three rather stout short teeth, 

 then a minute tooth and an obtuse loAver angle. Tlie upper and 

 lower borders are densely and very finely hairy, as are also the in- 

 tervals between the teeth (fig. 425). 



The maxilhe do not differ materially from those of B. rostratus 

 as figured by Iloek, except that there are several small spines above 



Fig. 41. — Balaxus rostratus apeutus. a, 14th segment of anterior ramus cirrus iv, 



MUCH ENLARGED TO SHOW DISTAL SPINULES. h, 27Tn SEGMENT OF ANTERIOR RAMUS 

 CIRRUS \l, BOTH FROM CaT. NO. 38667. C, FORM SUTURALIS, NO. 48025, 37th SEGMENT 

 CIRRUS VI. d, MANDIBLE. C, LABRUM. 



the two great spines (fig. 42c). There is a large spine in the middle 

 of the lower border, as in all of the B. Ixdanus group. 



The fii'st cirrus (fig. 42a) has very unequal rami of 15 and 27 

 segments, those of the posterior branch strongly protuberant at tlic 

 anterior side, with dense hair-tufts. The second and third cirri 

 also have unequal branches, the segments of both strongly protuber- 

 ant, with dense tufts. Cirrus ii has 15 and 19 segments; cirrus iii, 

 12 and 19. Both rami are rather well provided with spinules except 

 in the distal third. In cirrus iv, both rami have spinules along the 

 distal borders (fig. 41a, part of the fourteenth segment of anterior 

 ramus). Cirrus v has one or two rows of spinules near the distal 

 sutures of the segments. Cirri \y to vi are of the usual slender and 

 elongate shape, with subequal branches of about 35 segments. These 

 segments are convex anteriorly, each with 6 or 7 pairs of spines, 

 with some minute accessory spines at their bases, and having the 

 usual posterior sutural groups of small spines (fig. 42f/, fifteenth 



